In electric motors, in generator operating mode it is possible to produce sinusoidal alternating voltages. In order to supply the vehicle electrical network with energy, these voltages are transformed into direct voltages by power-electronic bridge circuits. Diodes are standardly used for this purpose.
In order to additionally make it possible to provide motoric operating states and at the same time to improve the efficiency of generator operation through an active rectification, these diodes can be replaced by MOSFETs or IGBTs. A suitable controlling of the MOSFETs or IGBTs can realize both motoric and also generator-based operating states. The packaging of the transistors is degraded for example by increasing breakage of the solder, or cracks in a bonding connection over the operating life, and therefore presents a risk of failure for the system as a whole.